Recently, various information processing systems have been developed in accordance with the rapid evolution of the information industry, and various recording methods and apparatus suitable to the respective information processing systems have been developed and employed.
A thermal transfer recording method is one type of system that has been widely used and this method requires a light-weight, compact, noise-free device having excellent operatability and ease of maintenance and may easily form color images. The thermal transfer recording method may be roughly grouped into two groups. One is a thermofusion type method and the other is a thermomobile type method.
The latter method involves a thermal transfer dye-providing material having a dye-providing layer containing a binder and a thermomobile dye on a support which is laid on a thermal transfer image-receiving material and heated from the side of the support of the dye-providing material to thereby transfer the thermomobile dye to the recording medium (thermal transfer image-receiving material) in accordance with the heated pattern to form a transferred image.
The thermomobile dye used in the thermomobile type method is a dye capable of being transferred from the thermal transfer dye-providing material to the thermal transfer image-receiving material upon sublimation or diffusion in a medium.
However, there are problems which are associated with known methods. For example, the images obtained by conventional thermal transfer image-receiving materials do not have a sufficient image density, and/or the storage stability of the images, especially the light-fastness, is not sufficient. Therefore, the hue of the images varies or the image density of the images lowers when the images are exposed to sun light or fluorescent light.
A means of improving the storage stability of images by adding an anti-fading agent to an image-receiving layer has been recognized. However, where a low molecular weight compound having a molecular weight of 1000 or less, such as an ordinary anti-fading agent, is added to an image-receiving layer, the transferred thermomobile dye diffuses in the image-receiving layer via the low molecular weight compound so that the storage stability of the formed image is defective. In particular, where the formed image is stored under high temperature conditions, various unfavorable problems of re-transferrence of the formed image or blurring of the same occur.